The Komatsu PC138US is designed for buyers who need the digging capability of a mid-size crawler excavator but still work where rear swing space is limited. Compared with smaller machines such as the PC78US, it moves into a substantially heavier class and offers greater digging reach, bucket capacity and working capability. That extra performance also means higher transport, undercarriage and operating requirements.
A used PC138US can suit road work, utilities, civil engineering, site preparation and construction in developed areas, but buyers should identify the exact generation before comparing machines. PC138US-8, PC138US-10 and PC138US-11 specifications differ. This guide focuses on deciding whether the PC138US class fits your work, understanding those generation differences, and checking the areas that can significantly affect the value of an individual used machine.
What Type of Buyer Is the PC138US For?
Komatsu positions the PC138US as a short-tail hydraulic excavator for applications ranging from confined pipe work to general civil engineering. The concept gives buyers an alternative to a conventional excavator when they need meaningful digging performance but have limited clearance behind the machine.
The PC138US class may be appropriate for work such as:
- Road construction and maintenance
- Urban civil engineering
- Water, sewer and drainage installation
- Foundation and structural excavation
- Site development
- Slope and bank work
- Truck loading
- General earthmoving
- Compatible hydraulic attachment work
This is not usually the first machine to choose for very small residential sites. Its operating weight is much greater than that of a mini excavator. The advantage appears when the job requires stronger digging performance, greater working range and better stability while rear clearance remains an important concern.
Why the Short-Tail Design Matters at This Size
The “US” concept is central to the PC138US family. Komatsu describes these machines as ultra-short or short-tail swing excavators designed for restricted working environments.
This can be particularly useful beside roads, structures, barriers and other equipment. A conventional excavator may need more space behind the tracks as the upper structure rotates. A PC138US is designed to reduce that rear projection.
Komatsu lists a 1,980 mm swing radius for one official PC138US-11 specification. Earlier PC138US generations were also designed around reduced tail swing.
That does not mean the excavator can operate safely within its track width alone. The boom, arm, bucket and upper structure still need adequate clearance. Buyers should consider the complete working envelope rather than only the rear counterweight.
PC138US-8, PC138US-10 and PC138US-11 Are Not the Same Machine
The PC138US has developed through several generations, and a used buyer should always check the suffix after the model name.
Official Komatsu information for the PC138US-8 lists a net engine output of 68.4 kW / 91.7 HP, an operating weight range of 13,480 to 13,850 kg and bucket capacities from 0.18 to 0.60 m³ for the referenced specification.
The later PC138US-10 was developed to meet Tier 4 Interim emissions requirements in relevant markets. Komatsu European data lists 72.6 kW / 97.3 HP, operating weights of approximately 13.7 to 14.9 tonnes and a bucket capacity up to 0.72 m³.
The PC138US-11 followed with further emissions, hydraulic, visibility and fuel-efficiency developments. A current Australian Komatsu specification lists 72.5 kW / approximately 97 HP, 15,500 kg operating weight and a 0.53 m³ bucket for that market configuration.
Specifications vary by model year, market, track configuration, boom, arm, bucket and optional equipment. Exact specifications should be confirmed for each individual machine.
Official Specification Examples
| Item | PC138US-8 | PC138US-10 | PC138US-11 |
|---|---|---|---|
| Machine classification | Short-tail crawler hydraulic excavator | Short-tail swing crawler excavator | Mid-size short-tail excavator |
| Engine power | 68.4 kW / 91.7 HP net | 72.6 kW / 97.3 HP in referenced European data | 72.5 kW / approximately 97 HP net in referenced Australian data |
| Operating weight | 13,480–13,850 kg | Approximately 13.7–14.9 tonnes | 15,500 kg in referenced Australian configuration |
| Bucket capacity | 0.18–0.60 m³ | Up to 0.72 m³ in referenced European specification | 0.53 m³ in referenced Australian configuration |
| Maximum digging depth | Depends on arm and configuration | 5.9 m in referenced European specification | 5.48 m with the specified standard arm in referenced Australian data |
The table is useful for understanding how the PC138US developed, but it should not be copied into a purchase contract as the specification of a particular used unit.
What Do You Gain by Moving Up to the PC138US Class?
The main gain is working capability. Compared with a smaller excavator, the PC138US can offer greater reach, digging depth, bucket volume and stability for demanding construction work.
For example, Komatsu's current PC138US-11 Australian specification gives a maximum digging depth of 5,480 mm and maximum reach at ground level of 8,180 mm with its specified 4.6 m boom and 2.5 m arm.
That additional capability can matter when excavating deeper utilities, preparing larger foundations or loading material over a longer working radius.
However, buyers should ask whether that capability will actually be used.
| Requirement | Question Before Buying |
|---|---|
| Digging depth | Does your normal excavation require the PC138US working range? |
| Production | Will a larger bucket improve daily output on your jobs? |
| Site access | Can a machine around this weight and width reach the work area? |
| Rear clearance | Does short-tail design provide a real advantage on your sites? |
| Attachments | Does the individual machine have suitable auxiliary hydraulics? |
| Transport | Can your trailer, road network and destination support this class? |
If a smaller excavator already completes your normal work efficiently, increasing machine size can raise costs without adding enough practical value.
The PC138US-8 Can Be an Important Used-Market Candidate
For buyers looking at Japanese used equipment, the PC138US-8 is a generation worth understanding separately.
Komatsu's official brochure identifies its diesel engine output at 68.4 kW / 91.7 HP net and shows operating weights from 13,480 to 13,850 kg in the referenced configurations. Bucket capacity ranges from 0.18 to 0.60 m³.
The brochure also emphasizes the machine's small tail swing, broader working range, multiple working modes, large monitor and maintenance access.
Age, however, makes inspection increasingly important. An older PC138US-8 with acceptable hours can still require significant spending if its undercarriage, hydraulic components or working equipment are heavily worn.
For this reason, compare purchase price together with expected repair cost rather than ranking used machines by price alone.
What Changed on Later PC138US Generations?
The PC138US-10 and PC138US-11 introduced changes that matter to some overseas buyers.
Komatsu developed the PC138US-10 around Tier 4 Interim emissions requirements in markets where those standards applied. The PC138US-11 then moved to Tier 4 Final / Stage IV technology for applicable markets.
The PC138US-11 also introduced developments such as improved engine and hydraulic efficiency, automatic idle shutdown and, on relevant specifications, Komatsu's KomVision camera system.
This creates an important buying decision. Newer emissions technology can provide environmental and efficiency advantages, but the buyer must also consider local access to appropriate fuel, diagnostic support, parts and knowledge of emissions-control systems.
Market specification matters here. Komatsu also offers a PC138US-11 non-Tier-4 version in some regions. Do not assume every PC138US-11 has the same after-treatment system simply from the model designation.
Eight Areas That Deserve Attention on a Used PC138US
1. Identify the Exact Model and Serial Number
Start with identification rather than condition.
Confirm the full model suffix and serial number shown on the machine. This helps distinguish generations and makes it easier to verify the relevant specification, engine and parts information.
2. Check Engine Starting and Running Condition
If practical, observe a cold start. Check for difficult starting, unstable idle, abnormal smoke, unusual noise, excessive vibration and fluid leaks.
On later emissions-controlled machines, check for warning lights or fault indications. Do not assume an emissions-related warning is a minor electrical issue without further investigation.
3. Test the Hydraulic System Under Movement
The hydraulic system operates the working equipment, swing and travel functions, so its condition strongly affects productivity.
Operate the boom, arm and bucket through combined movements rather than testing each function only once. Check swing operation and travel as well.
Look for:
- Hydraulic oil leakage
- Damaged cylinder rods
- Slow or inconsistent movement
- Unusual pump noise
- Excessive cylinder drift
- Damaged hoses and fittings
Komatsu identifies the PC138US-11 hydraulic architecture as its HydrauMind system. Hydraulic details vary between generations, so repair and diagnostic requirements should be matched to the actual machine.
4. Inspect Boom, Arm and Structural Areas
A PC138US may have completed heavy excavation, slope work, demolition support or demanding attachment work.
Inspect the boom, arm, pin bosses and cylinder mounting points for cracks, deformation and repairs. Pay attention to welds or reinforcement plates that appear different from the original construction.
A repaired machine is not automatically unsuitable, but the location, quality and reason for the repair should be understood.
5. Measure Pin and Bushing Wear
Play in the bucket linkage and working equipment becomes more important on a machine of this size because loads are higher than on a small mini excavator.
Excessive looseness can affect digging accuracy and indicate future replacement work. Check the bucket linkage, arm-to-bucket connection, boom-to-arm area and boom foot.
6. Treat the Undercarriage as a Major Cost Item
The undercarriage should have a major influence on purchase price.
Inspect:
- Track links and shoes
- Sprocket teeth
- Bottom rollers
- Carrier rollers
- Front idlers
- Track tension
- Track frame
- Uneven wear between sides
A machine can look clean above the tracks while requiring substantial undercarriage work below them.
7. Check Swing Operation and Slew Play
Rotate the upper structure in both directions and listen for abnormal sound. Assess stopping behavior and look for excessive movement in the swing bearing area.
Because short-tail machines may spend considerable time working and rotating in confined environments, swing-system condition deserves specific attention.
8. Confirm Attachment History and Hydraulic Piping
Ask what attachments the machine previously used when that information is available.
A machine that has spent many hours with a hydraulic breaker can show a different wear pattern from one used primarily for earthmoving.
If you intend to use a breaker, crusher, grapple or another hydraulic attachment, verify the installed auxiliary circuit and the flow and pressure requirements of the attachment. Do not assume that visible piping guarantees compatibility.
Why Operating Hours Need Context on a PC138US
Hour meter readings are helpful, but the workload represented by one operating hour can vary greatly.
A machine used mainly for general excavation may experience different wear from one used for demolition, rock breaking or severe slope work.
Compare hours with:
- Maintenance information when available
- Previous application
- Hydraulic condition
- Undercarriage remaining life
- Pin and bushing movement
- Engine condition
- Cab and control wear
- Structural repair history
A lower-hour machine with poor maintenance or severe previous use may not be the better purchase.
PC78US or PC138US: Which Class Makes More Sense?
The previous step in the Komatsu short-tail range can be represented by a machine such as the PC78US. The move to the PC138US is substantial enough that buyers should base the decision on workload rather than preference for a larger machine.
| Consider the PC78US Class When... | Consider the PC138US Class When... |
|---|---|
| Jobsites and transport access favor a smaller machine. | Your sites can physically support a machine above 13 tonnes. |
| Utility and general construction tasks are moderate. | Deeper excavation and higher production are regular requirements. |
| Transport flexibility is a major priority. | You already have suitable heavy-equipment transport arrangements. |
| Bucket and working range requirements are smaller. | You need greater working range and bucket capacity. |
| Lower operating costs are more important than maximum production. | Higher jobsite productivity can justify the larger machine. |
Choose according to the work that represents most of your operating time, not the largest project you might encounter occasionally.
Do Not Use One Lifting-Capacity Number
Lifting capacity for an excavator changes according to the machine configuration and the position of the load.
If the PC138US will be used to handle pipes or other materials, use the lifting chart for the exact generation, arm, track configuration and operating position.
The permissible load can change with lifting radius and height, and limitations may come from either hydraulic capability or machine stability.
Buyers should also check local regulations and required safety equipment before planning lifting work with an excavator.
Shipping a PC138US from Japan
At approximately 13 to 15 tonnes or more depending on generation and configuration, the PC138US requires more shipping planning than compact mini excavators.
Actual transport dimensions and weight should be obtained for the individual machine before requesting freight.
Check:
- Exact PC138US generation and serial number
- Overall transport length
- Overall width
- Overall height
- Actual machine or shipping weight
- Bucket and additional attachments
- Track configuration
- Destination port
- Available vessel and shipping-line requirements
Container, RORO, flat rack or breakbulk arrangements may be considered depending on machine dimensions, destination, port, shipping line and current shipping conditions. The model name alone is not enough to determine the correct method.
Removal or repositioning of attachments may sometimes affect transport dimensions, but any shipping preparation should be confirmed for the individual machine and planned according to the selected transport method.
A Practical PC138US Buying Checklist
- Confirm the generation. Identify PC138US-8, PC138US-10, PC138US-11 or another exact specification.
- Verify the serial number. Match the machine identity with available information.
- Check engine and emissions equipment. Requirements vary significantly by generation and market.
- Test hydraulic operation. Evaluate combined movements as well as visible leaks.
- Inspect structural components. Look closely at boom, arm and high-stress areas.
- Evaluate the undercarriage. Include its remaining life in your purchase budget.
- Check pins and bushings. Excessive play can mean additional repair costs.
- Confirm hydraulic piping and attachments. Do not rely only on listing photos.
- Verify dimensions and weight. Use the actual machine for freight planning.
- Compare capability with your work. Make sure the larger machine will deliver a practical advantage.
Buying a Used Komatsu PC138US from Japan
Japanese used PC138US excavators can differ considerably in generation, hours, specification and previous application. Comparing individual condition is therefore more useful than searching for one supposedly ideal year or hour range.
You can check current Japanese used machinery available at EVERYCAR.jp. Stock changes regularly, so availability of a particular PC138US generation or configuration should be confirmed from current listings.
You can also use the Japanese Used Machinery & Heavy Equipment Guide | 100 Articles to compare other excavator sizes and machinery buying considerations before selecting a machine.
Should You Buy a Used Komatsu PC138US?
The PC138US is a strong candidate when your work has moved beyond the practical capacity of smaller excavators but restricted rear clearance still matters. Its short-tail design is particularly relevant to road, utility and urban construction, while its size provides substantially greater digging and earthmoving capability than compact mini excavators.
Its larger size also makes condition assessment more financially important. An undercarriage, hydraulic or structural issue on this class of machine can represent a meaningful ownership cost. Identify the exact generation first, then evaluate condition, configuration, attachments and transport requirements together.
If you are looking for a Komatsu excavator or other used machinery from Japan, you can contact EVERY with your preferred manufacturer, model, size, budget, intended work and destination. Those details provide a clearer basis for comparing available machinery with your actual operating requirements.
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